19
votes
Accepted
For electricity use, which is better: Turning all appliances on at the same time, or spread out?
The "surge" that the electric utility was referring to is the demand charge:
The kWh charge (consumption) is the measurement of the amount of energy the building uses over the given period ...
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13
votes
What form of electrical lighting has the smallest energy-footprint?
i signed up just so i could make this comment. THelper♦ provided a good link to a DOE report on this topic, which i was researching because my roommate is skeptical about the advantages of efficient ...
- 231
13
votes
Are fuel cell electricity generators a sustainable way of making electricity?
No. There is no readily available supply of net-positive-energy hydrogen on Earth, where most human power usage takes place. Hydrogen fuel cells may be a useful component of a total energy system ...
- 1,594
11
votes
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Transmit solar over multiple time-zones?
Yes, we can. Estimates vary of the losses in long-distance HVDC (high-voltage direct current) transmission, but they're around 3-4% per 1000 km. Now, those operate at far higher voltages than you've ...
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11
votes
Getting power from an innovative new mechanism
No, you cannot get more energy out than you put in.
No, you cannot invent a perpetual motion machine.
- 14.7k
10
votes
Accepted
Is electricity used at night more likely to be renewable?
In Ireland, electricity is equally likely to be from renewable sources during the day as during the night
ENTSO-E, the European Network of Transmission System Operators for Electricity, provides a ...
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8
votes
Do USB outlets waste energy just like conventional wall warts?
Electronically they're the same and will waste as much energy as a conventional adaptor. Depending on your electrical regulations they may be forced to be at the good end of adaptor efficiency, or ...
- 2,077
8
votes
Hydro-electric generation from roof-collected rainwater
If it's a very simple motor then it may be possible just to run it backwards to generate electricity. If it's got electronic controls, probably not.
But is it worth it? Do a quick calculation of the ...
- 14.7k
8
votes
Accepted
Can 140 square miles of solar panels power the US?
Summary
No, that's way too little. I think "140 miles square" has got mangled into "140 square miles".
Running the numbers
Following on from one of Elon Musk's presentations, which ...
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8
votes
Accepted
How much energy would it cost to stabilize 2 tons of water at 70 degrees?
The stabilisation energy rate will be exactly exactly equal to the rate at which energy is lost.
Assuming the tank is closed, so there are no evaporative losses, there are two other ways energy is ...
- 14.7k
8
votes
How to ensure you are using efficient chargers for cell phones, laptop computers, and other electronic devices?
Power ratings -- choose level VI
Take a look at any external power supply (EPS) you have lying around -- you should notice, along with all the regulatory markings, a roman numeral I through VI in a ...
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7
votes
Accepted
Which is more energy efficient, a washing machine express wash, or normal?
I think a "general principle" is that "express wash" usually means one or more of the following
reduce the wash cycle
reduce the spin cycle
skip a rinse cycle (e.g. by not using any softener)
etc.
...
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7
votes
Accepted
Energy saving lamps suggestion
The wattage given on the fixture refers to the maximum that can safely be used. That will be dictated by two things: The internal wiring of the fixture, and the heat that it can tolerate.
In reality ...
- 3,660
7
votes
Electrical usage data logging with wireless data transfer
It sounds like the Kill A Watt wireless might be what you are after. For more alternatives keep reading.
There is another product line called the Watts-Up that has USB connections to computers on ...
- 862
7
votes
How much energy do wall outlets with USB waste when not actively charging?
In most countries, legislation limits the amount of power a device on standby, i.e. under power but not performing a function, are allowed to use. In Europe it's 0.5 Watts (see EC Regulation No. 1275/...
- 161
6
votes
Anything similar to GravityLight that can be readily purchased?
The big advantage of GravityLight is that you can pull the weight once and then you have electricity for a relatively long period (I read somewhere it's 30 minutes). This is ideal when you need to ...
- 14.4k
6
votes
Accepted
How much, if any, does resolution effect the net power consumption of watching online video?
The Natural Resources Defense Council commissioned a study in late 2015 to understand the energy consumption from 4K TVs, titled The Big Picture: Ultra High-Definition Televisions Could Add $1 Billion ...
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6
votes
Any way for microinverter PV array to power a house when the grid is down?
tl;dr: Because of how the grid and your inverters work, it's unlikely that there is a solution for your current system. You will either need to set up a communication network with your microinverters ...
- 11.7k
6
votes
For electricity use, which is better: Turning all appliances on at the same time, or spread out?
The primary issue being described is Peak Demand charge. The description in LShaver's answer explains a lot of that, but there are a few more pieces that I think are important:
Why does peak demand ...
5
votes
Accepted
Is there a way to tell (or estimate) the electricity consumption of an arbitrary household item?
The easiest way is to buy a meter that plug into the power outlet and the device you want to measure is plugged into the meter. Something like this:
Depending on the meter you buy, it will measure ...
- 3,417
5
votes
How would one go about judging the sustainability of BitCoin or other cryptocurrency
Electricity is just a vector of energy: it is neither sustainable nor unsustainable per se. It depends how it is generated and how it is used.
No ponzi scheme is economically sustainable; and BitCoin ...
- 14.7k
5
votes
What is an easy way to cool off during the summer without electricity?
I developed a simple strategy suitable for living in a flat that is not on the top floor:
When you wake up, close all windows and put the blindfolds down. This allows to prevent sun rays and hot air ...
- 237
5
votes
What is an easy way to cool off during the summer without electricity?
I am in Thailand now, it is the hottest time of year, relentless 40C and sun every day. No air conditioning.
I survive by staying indoors during the hottest time of day, getting my clothes wet. ...
- 279
5
votes
Accepted
Does it make any difference to charge my electronic devices using an USB port?
To give a definite answer would require a lot of research and it would probably be quite impossible to give a "for sure" answer because there are some variables. Some computer power supplies are much ...
- 676
5
votes
Does it make any difference to charge my electronic devices using an USB port?
Computer PSUs generally only hit their rated efficiency when well loaded. Most desktop PCs have larger PSUs than they need, to allow for expansion, and so they are not fully loaded. Consequently it is ...
- 3,660
5
votes
What's the average efficiency of pumped hydroelectric energy storage facilities?
In this question about rooftop hydro I covered the efficiency question almost as an aside. I can't find an actual plant with efficiency over 80%, only claims that that might be possible. The average ...
- 3,856
5
votes
Is leaving an electric oven on to heat bad for the oven?
Have to start by saying, a much better idea to heat with an electric than with a gas stove: as mentioned in this excellent question, gas stoves emit toxic carbon monoxide.
Having said that, there are ...
- 151
5
votes
Is Tesla Powerwall a good investment?
No it is not. Your calculations of 13year ROI is based on the assumption that charging the power wall is free during the day time. It is not.
Depending on your locale, either you need to factor in ...
- 360
5
votes
Accepted
Temperature for hot water cylinder
Yes, higher thermostat temperatures mean more electricity consumption. Also your thermostat manual is right, bacteria growth is a valid concern.
The ideal conditions for the Legionella bacteria to ...
- 14.4k
Only top scored, non community-wiki answers of a minimum length are eligible